Inappropriate Subcutaneous Implantable Cardioverter-defibrillator Shocks—A Rare Case of Triple Counting

Sudden cardiac death (SCD) caused by ventricular tachyarrhythmias is a significant contributor to cardiovascular deaths worldwide. Implantable cardioverter-defibrillators (ICDs) have shown efficacy in preventing and reducing mortality from SCD, but traditional transvenous ICDs have inherent challenges and drawbacks, such as lead fractures, lead-associated endocarditis, and lead failure. To address these issues, subcutaneous ICDs (S-ICDs) have been developed. S-ICDs lack pacing capacity but are a valid alternative for patients at high risk for infection or with difficult venous access. Pre-implantation screening can help prevent inappropriate device shocks. We present a case in which a patient received inappropriate S-ICD therapy, which was attributed to the triple counting of P-, R-, and T-waves in a patient with sinus rhythm. This is an unusual occurrence, and, to the best of our knowledge, there are only a limited number of case reports documenting inappropriate shocks due to the oversensing of P-waves and T-waves.